1. Technical Field
The present invention relates liquid ejection apparatuses. More specifically, the present invention relates to an apparatus and method of testing whether the recording liquid is ejected from a plurality of nozzles in a print head.
2. Related Art
Generally, ink jet recording apparatuses print on recording media by ejecting recording liquid from nozzles provided in print heads. When the recording liquid is not ejected from the nozzles the print images fail to print correctly. In order to determine if the recording liquid has successfully been ejected from the nozzles, various technological methods for testing whether recording liquid is ejected properly have been proposed. For example, one technology detects the change in the electric field intensity between electrodes in the apparatus by using charged ink droplets (see Japanese Patent JP-A-59-178256). One difficulty in using the charged ink droplets is that the ink droplets have small volumes, making it difficult to detect the change in the electric field intensity using one ink droplet. In response, another technology acquires the change (voltage change) of detectable electric field intensity by ejecting a plurality of ink droplets from each nozzle (see Japanese Patent JP-A-11-170569).
In recording apparatuses capable of printing high definition images, such as printers used for printing photographs, the print heads have hundreds to thousands of nozzles. Accordingly, when a test for ejection of recording liquid from nozzles is performed for these recording apparatuses by using known the charged ink droplet technology described above, the amount of time required to test the many test nozzles and a plurality of ink droplets is extensive.
In addition, in the technology disclosed in the Japanese JP-A-59-178256 and JP-A-11-170569 patents, the ejection timing of the ink droplets among nozzles includes a standby time between the ejection of ink droplets from one nozzle to the ejection of ink droplets from the next nozzle. Accordingly, when the test is performed for all the nozzles in a high definition apparatus, the time required for the test is lengthened due to the standby time.
In addition, the Japanese JP-A-59-178256 and JP-A-11-170569 applications, fail to provide a detailed description of the detected change in the voltage in relation to the change of detected electric field intensity due to the ejection of ink droplets.